The invention relates to a door for closing an opening in a chamber wall of a vacuum chamber in reference to the atmosphere comprising a sealing element, which is fastened to at least one rod and which is adjustable between an open position, in which it releases the opening, an intermediate position, in which it covers the opening but raised from a seat surrounding the opening, and a closed position, in which it is pressed to the seat, a door body carrying at least one rod and the sealing element, and which can be tilted about a tilting axis in order to adjust the sealing element between the intermediate position and the closed position in reference to the chamber wall, and at least one tilting actuator, which comprises an inner cavity, into which a compressed gas can be introduced to tilt the door body about the tilting axis.
Doors are known in various embodiment for sealing openings in vacuum chambers. Such doors serve for example to allow the insertion work pieces into a lock bay and/or load-lock chamber, from which the work pieces after evacuation of the chamber are transferred into different chambers in which processing steps are performed under vacuum conditions.
A vacuum door is known for example from U.S. Pat. No. 6,056,266. In order to press the sealing element against the seat surrounding the opening, based on a retracted open position of the sealing element, in which it completely releases the opening, an L-shaped motion is performed. Here, in a first section of the adjustment path traveled, the sealing element is displaced via a first drive parallel in reference to the opening and/or the seat until the sealing element covers the opening but is still spaced apart from the seat. In a second adjustment path the sealing element is pressed via a second drive perpendicular in reference to the plane of the opening and/or the seat until the sealing element is pressed against the seat and the opening is sealed in a vacuum-tight fashion by the seal pressing against the sealing surface. The first and second drives are formed by piston-cylinder units. In order to form a subsequent control for the correct L-motion of the sealing element the piston surfaces of the piston-cylinder units acting in the opening and the closing direction are of different size. The piston surface acting in the closing direction is permanently impinged with the system pressure of the compressed air driving the piston-cylinder units. When the door is to be closed, starting from its open position, the piston surfaces of the first and second drive acting in the opening direction are rendered free from pressure, i.e. the respective cylinder chambers are evacuated. When the door is to be opened, starting from its closed state, the piston surfaces acting in the opening direction are impinged with the system pressure of the compressed air. Only a single switching valve is required for the correct performance of the L-motion during the opening and closing process of the door.
Additional vacuum doors, in which the sealing element performs a L-shaped motion during the opening and closing process of the vacuum door, are known from U.S. Pat. No. 6,899,316 B2, US 2007/0272888 A1, and U.S. Pat. No. 6,916,009 B2.
From DE 196 33 798 A1 a vacuum door of the type mentioned at the outset is known, in which the displacement along the first section of the displacement path also occurs in the above-described manner. In order to press the sealing element to the seat, beginning from a position covering the opening but separated from the seat, here the door body of the door is guided in a displaceable fashion by rods with the sealing element fastened thereon and can be tilted in reference to the chamber wall of the vacuum chamber comprising the opening. Via piston-cylinder units the door body is tilted about the tilting axis in order to press the sealing element to the seat and to separate it therefrom. In order to completely open the door, the sealing element, separated from the seat, is pulled back by the rods being axially displaced by piston-cylinder units.
A vacuum valve is disclosed in WO 2009/070824 A1 in which also the use as a vacuum door is described. Here, the sealing element can also be arranged outside the vacuum chamber and provided to seal an opening in a chamber wall. The opening and closing of the sealing element occurs only via one drive (which may provide two piston-cylinder units as actuators), by which the rods to which the sealing element is fastened, can be axially displaced. Based on an open position, in which the sealing element completely releases the opening, the sealing element is first displaced parallel in reference to the plane of the opening and/or the seat surrounding the opening until the sealing element approaches the guiding elements arranged at both sides of the opening and comprising guiding surfaces extending at an angle in reference to the plane of the seat. By these guiding surfaces the sealing element is displaced via an end section of the displacement path prior to reaching its sealed position at an angle in reference to the plane of the seat until the sealing element is made to contact the seat and the seal is pressed against the sealing surface.
From U.S. Pat. No. 6,471,181 B2 a fastening of a valve plate is known at a valve rod, in which the valve plate can be tilted about an axis aligned perpendicular in reference to the axis of the valve rod.
A vacuum valve is discernible from US 2007/0290157 A1 in which a sealing element comprises a valve plate for sealing the valve opening. Inside the sealing element a setting piston is arranged, with tappets being fastened thereon, which are supported on the valve housing for pressing of the valve seat against the valve plate. At least one operating chamber of the sealing element, which can be impinged with compressed gas to displace the setting piston, is limited by a diaphragm seal.